Growth of thick gan films on rf sputtered ain buffer layer by hydride vapor phase epitaxy

Abstract

High crystalline quality thick GaN films were grown by vapor phase epitaxy using GaC13 and NH 3. The growth rate was in the range of 10 ~ 15 ~m/h. GaN films grown at higher temperatures (960~ 1020 ~ were single crystalline with smooth surface morphologies. No chlorine impurity was incorporated in these films during growth. The best crystalline quality and surface morphology of grown films was achieved by sputtering a thin A1N buffer layer, prior to growth. According to reflection high energy electron diffraction and atomic force microscopy measurements, as-sputtered AlN buffer layer was amorphous with root means square roughness of 0.395 nm and then crystallized during the GaN growth. This improved the GaN growth due to more uniform distribution of GaN nucleation. Rutherford backscattering channeling experiments produced the lowest value from the GaN film grown on a-AlzO 3 with a 500/k A1N buffer layer at 1020~

Group III nitride and SiC based MEMS and NEMS: materials properties, technology and applications

“…In contrast to the application of porous substrates, the growth of group III nitrides on nanocrystalline interlayers was rarely investigated. First studies were performed by halide vapour phase epitaxy (HVPE) of GaN on sputtered AlN on sapphire substrates [164,165]. By the MOCVD overgrowth of sputtered nanocrystalline AlN films on sapphire, fully relaxed GaN layers and AlGaN/GaN heterostructures were realized [166].…”

Effects of Growth Temperatures on Crystal Quality of GaN by Vapor Phase Epitaxy Using GaCl3 and NH3

“…6,7) Subsequently, thermodynamic analysis and preliminary experiments were presented as the first demonstration of the VPE growth of GaN using GaCl 3 . [8][9][10] The thermodynamic analysis suggests that the formation of GaN is driven by the reaction of GaCl and NH 3 , where the GaCl is formed from GaCl 3 . Direct reaction between GaCl 3 and NH 3 is a possible path for the formation, since the decomposition of GaCl 3 might be insufficient depending on the system configuration including the nozzle positions.…”

Emergence of high quality sputtered III-nitride semiconductors and devices

“…Ex-situ sputtered AlN buffer layers have been found early on to be effective in reducing defect density in the follow up HVPE-grown GaN on flat [5][6][7][8] and later on patterned [9,10] sapphire as well as on Si (111) substrates [11]. In one of the pioneering works, Lee et al [8] employed 10-100 nm thick AlN layers deposited by radio frequency (rf) reactive sputtering on a-and c-plane sapphire substrates at a low temperature of 50 °C.…”

“…Ex-situ sputtered AlN buffer layers have been found early on to be effective in reducing defect density in the follow up HVPE-grown GaN on flat [5][6][7][8] and later on patterned [9,10] sapphire as well as on Si (111) substrates [11]. In one of the pioneering works, Lee et al [8] employed 10-100 nm thick AlN layers deposited by radio frequency (rf) reactive sputtering on a-and c-plane sapphire substrates at a low temperature of 50 °C. The as-sputtered AlN films were very smooth (root mean square roughness, rms, of 0.3-1.5 nm) and amorphous or micro-crystalline, but, when exposed to typical HVPE growth temperatures (∼1000 °C), hexagon-shaped crystal grains formed, and the surface roughness drastically increased to 15 nm.…”